US20020094167A1 - Dispersive optical waveguide array - Google Patents
Dispersive optical waveguide array Download PDFInfo
- Publication number
- US20020094167A1 US20020094167A1 US09/963,495 US96349501A US2002094167A1 US 20020094167 A1 US20020094167 A1 US 20020094167A1 US 96349501 A US96349501 A US 96349501A US 2002094167 A1 US2002094167 A1 US 2002094167A1
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- Prior art keywords
- array
- circle
- coupler
- waveguides
- waveguide
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/12007—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer
- G02B6/12009—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer comprising arrayed waveguide grating [AWG] devices, i.e. with a phased array of waveguides
- G02B6/12014—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer comprising arrayed waveguide grating [AWG] devices, i.e. with a phased array of waveguides characterised by the wavefront splitting or combining section, e.g. grooves or optical elements in a slab waveguide
Definitions
- the invention relates to a dispersive optical waveguide array and more particularly to such an array using silicon rib waveguides.
- Dispersive optical arrays are known for use in multiplexers and demultiplexers and may comprises an array of optical waveguides of different pathlengths thereby introducing phase changes between optical signals transmitted through the different waveguides within the array.
- Such a system may comprise a plurality of waveguides each arranged around a curved path so as to introduce different optical pathlengths.
- Such devices may include optical couplers at the input and output ends of the array to allow serial connection of the array with input and output waveguides.
- the invention provides a dispersive optical waveguide device comprising an array of curved silicon rib waveguides providing optical paths in parallel between a first optical coupler at one end of the array and a second optical coupler at an opposite end of the array, the ends of the array waveguides adjacent said second coupler being distributed around a first arcuate edge of said second coupler forming part of a first circle, and a plurality of connecting waveguides terminating at a second arcuate edge of said second coupler facing said first arcuate edge of the second coupler, said second arcuate edge forming part of a second circle having a radius of curvature which is half the radius of curvature of the said first circle and having its perimeter coincident with the perimeter of the first circle adjacent the said ends of the array waveguides.
- the said ends of the array waveguides are inclined to each other so as to focus at said second arcuate edge of the second coupler.
- said connecting waveguides are inclined towards each other at said second arcuate edge so as to focus at said first arcuate edge of said second coupler.
- said first optical coupler has two facing arcuate edges, one adjacent an end of the waveguide array forming part of a third circle and the other forming part of a fourth circle, the fourth circle having a radius of curvature one half that of the third circle and having its perimeter coincident with the perimeter of the third circle adjacent said array of waveguides.
- an input waveguide is connected to the first optical coupler at the arcuate edge on said fourth circle facing said waveguide array.
- said input waveguide is a silicon rib waveguide.
- said first and third circles have the same radius of curvature.
- said second and fourth circles have the same radius of curvature.
- each of said first and second optical couplers comprise a slab region of silicon.
- connecting waveguides each comprise a silicon rib waveguide.
- the waveguide device may be arranged to operate as a multiplexer or demultiplexer.
- the waveguide device may comprise a single integrated silicon chip device.
- FIG. 1 shows a prior art construction of a silicon rib waveguide for use in accordance with this invention
- FIG. 2 is a schematic view of a dispersive waveguide array in accordance with the invention.
- FIG. 3 shows in more detail one waveguide used in the array of FIG. 2, and
- FIG. 4 shows in more detail the arrangement of waveguides in an optical coupler used in FIG. 2.
- This embodiment comprises a single chip integrated silicon device having a plurality of silicon rib waveguides together with other optical circuitry.
- the structure of the silicon insulator rib waveguide is of known type and is shown in FIG. 1.
- the upstanding rib 11 is formed on a silicon layer 12 .
- a silicon substrate 13 is covered with a silicon dioxide layer 14 immediately below the silicon layer 12 .
- a silicon dioxide coating 15 is formed over the upper surface of the silicon and over the rib 11 .
- the rib 11 may be formed by etching two trenches 8 and 9 along either side of the rib 11 in a slab of silicon so that the top of the rib is level with the remainder of unetched slab.
- a dispersive optical waveguide array is formed on a single integrated silicon chip 20 .
- a plurality of waveguides including an input rib waveguide 21 and a plurality of output rib waveguides 22 are formed on the chip each having the construction shown in FIG. 1.
- the chip 20 provides a uniform thickness planar slab of silicon in which the rib waveguides are formed between elongated etched trenches on both sides of each rib.
- the input and output waveguides are connected to respective external optical fibres 23 and 24 .
- On the silicon base 20 is formed an array 25 consisting of a plurality of similar rib waveguides each curved and providing optical paths in parallel with each curved waveguide lying side by side in the array.
- a single waveguide from the array is shown in more detail at 26 in FIG. 3. This has a central curved region terminating in a straight input end 27 and a straight output end 28 . It will be understood that such dispersive arrays may be used as multiplexers or demultiplexers and consequently the direction of light may be changed such that the input and output positions are interchangeable.
- the input end 30 of the array has the straight portions 27 of each waveguide terminating along an arcuate surface of an optical coupler 31 .
- the coupler 31 comprises unetched silicon slab having the same depth as the ribs of the rib waveguides. The etched trenches along opposite sides of each rib terminate at two facing arcuate edges of the coupler 31 .
- the ends 30 of the array of waveguides terminate at one of the arcuate surfaces of the coupler marked 33 and the input waveguide 21 terminates on the opposite arcuate face of the coupler marked 32 .
- the input waveguide 21 is arranged to be directed at the centre of the ends 30 of the waveguide array.
- the ends 30 of the waveguide array are themselves on the arcuate surface 33 which forms part of a circle of radius R.
- the facing arcuate surface 32 forms part of a circle of half the radius R but having its perimeter coincident with the arcuate surface 33 adjacent the ends 30 of the waveguide array.
- the straight ends 27 of the waveguide array 25 are inclined inwardly towards each other so as to focus at the end of the input waveguide 21 on the arcuate edge 32 of the coupler 31 .
- a similar optical coupler 40 is provided between the other end 41 of the array 25 and the output rib waveguides 22 .
- the ends 41 of the array 25 are spaced around a first arcuate edge of the coupler 40 , the arcuate edge forming part of a circle 42 having a radius R.
- the output waveguides 22 have their inner ends 43 terminating adjacent the further arcuate edge 44 forming part of a further circle 45 having a radius of one half R.
- the circle 45 has its periphery coincident with the arcuate edge of circle 42 adjacent the ends 41 of the waveguide array 25 .
- the straight ends 28 of the array 25 are again inwardly inclined towards each other so as to focus onto the perimeter of circle 45 adjacent the ends 43 of the output waveguides 22 .
- the output waveguides 22 which are curved across the chip 20 have straight end portions 43 inclined towards each other so as to be focussed onto the perimeter of circle 42 immediately adjacent the ends 41 of the waveguides in the array 25 .
- the wavefront leaving the output end of the dispersive array is focussed onto the or each output waveguide.
- the physical separation between adjacent curved waveguides in the array 25 there will be some coupling of the wavefront towards the output end of the array due to the close physical proximity of adjacent waveguides.
- the coupling of the wavefront between adjacent waveguides is much less than occurs with silica or with InP devices.
- the use of the Rowlands circle arrangement is such that the ends of the output waveguides 43 are located on the arc 44 which is much closer to the output ends 41 of the array than would be the case when using both arcs on a common circle.
- the arrangement of the optical coupler 40 is shown in greater detail in FIG. 4 and illustrates the focussing of the waveguides 25 onto position 50 which is midway across the array of output waveguides 22 .
- the output waveguides 22 are inclined inwardly so as to focus onto point 51 which is located midway across the array of waveguides 25 .
- This figure shows the coupler region 40 as being part of the unetched silicon slab with each wave guide being formed as an unetched rib remaining between two trenches etched in the slab. The etched trenches terminate at the arcs 42 and 44 leaving the ribs running into the slab region forming the couplers 31 and 40 .
- the invention is not limited to the details of the foregoing example.
- more than one input waveguide 21 may be provided.
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Integrated Circuits (AREA)
Abstract
A dispersive optical waveguide device comprising an array of curved silicon rib waveguides providing optical paths in parallel between a first optical coupler at one end of the array and a second optical coupler at an opposite end of the array. The ends of the array waveguides adjacent to the second coupler are distributed around a first arcuate edge of the second coupler forming part of a first circle. A plurality of connecting waveguides terminating at a second arcuate edge of the second coupler face the first arcuate edge of the second coupler. The second arcuate edge forms part of a second circle having a radius of curvature which is half the radius of curvature of the first circle and has its perimeter coincident with the perimeter of the first circle adjacent the ends of the array waveguides.
Description
- The invention relates to a dispersive optical waveguide array and more particularly to such an array using silicon rib waveguides.
- Dispersive optical arrays are known for use in multiplexers and demultiplexers and may comprises an array of optical waveguides of different pathlengths thereby introducing phase changes between optical signals transmitted through the different waveguides within the array. Such a system may comprise a plurality of waveguides each arranged around a curved path so as to introduce different optical pathlengths. Such devices may include optical couplers at the input and output ends of the array to allow serial connection of the array with input and output waveguides.
- It is an object of the present invention to provide an improved system of coupling input and/or output waveguides through optical couplers at the ends of such a dispersive rib waveguide array.
- The invention provides a dispersive optical waveguide device comprising an array of curved silicon rib waveguides providing optical paths in parallel between a first optical coupler at one end of the array and a second optical coupler at an opposite end of the array, the ends of the array waveguides adjacent said second coupler being distributed around a first arcuate edge of said second coupler forming part of a first circle, and a plurality of connecting waveguides terminating at a second arcuate edge of said second coupler facing said first arcuate edge of the second coupler, said second arcuate edge forming part of a second circle having a radius of curvature which is half the radius of curvature of the said first circle and having its perimeter coincident with the perimeter of the first circle adjacent the said ends of the array waveguides.
- Preferably the said ends of the array waveguides are inclined to each other so as to focus at said second arcuate edge of the second coupler.
- Preferably said connecting waveguides are inclined towards each other at said second arcuate edge so as to focus at said first arcuate edge of said second coupler.
- Preferably said first optical coupler has two facing arcuate edges, one adjacent an end of the waveguide array forming part of a third circle and the other forming part of a fourth circle, the fourth circle having a radius of curvature one half that of the third circle and having its perimeter coincident with the perimeter of the third circle adjacent said array of waveguides.
- Preferably an input waveguide is connected to the first optical coupler at the arcuate edge on said fourth circle facing said waveguide array.
- Preferably said input waveguide is a silicon rib waveguide.
- Preferably said first and third circles have the same radius of curvature.
- Preferably said second and fourth circles have the same radius of curvature.
- Preferably each of said first and second optical couplers comprise a slab region of silicon.
- Preferably said connecting waveguides each comprise a silicon rib waveguide.
- The waveguide device may be arranged to operate as a multiplexer or demultiplexer.
- The waveguide device may comprise a single integrated silicon chip device.
- An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings in which:
- FIG. 1 shows a prior art construction of a silicon rib waveguide for use in accordance with this invention,
- FIG. 2 is a schematic view of a dispersive waveguide array in accordance with the invention,
- FIG. 3 shows in more detail one waveguide used in the array of FIG. 2, and
- FIG. 4 shows in more detail the arrangement of waveguides in an optical coupler used in FIG. 2.
- This embodiment comprises a single chip integrated silicon device having a plurality of silicon rib waveguides together with other optical circuitry. The structure of the silicon insulator rib waveguide is of known type and is shown in FIG. 1. The upstanding rib11 is formed on a
silicon layer 12. Asilicon substrate 13 is covered with asilicon dioxide layer 14 immediately below thesilicon layer 12. Asilicon dioxide coating 15 is formed over the upper surface of the silicon and over the rib 11. The rib 11 may be formed by etching twotrenches 8 and 9 along either side of the rib 11 in a slab of silicon so that the top of the rib is level with the remainder of unetched slab. - In the single chip embodiment of FIG. 2, a dispersive optical waveguide array is formed on a single integrated
silicon chip 20. A plurality of waveguides including aninput rib waveguide 21 and a plurality ofoutput rib waveguides 22 are formed on the chip each having the construction shown in FIG. 1. Thechip 20 provides a uniform thickness planar slab of silicon in which the rib waveguides are formed between elongated etched trenches on both sides of each rib. The input and output waveguides are connected to respective externaloptical fibres silicon base 20 is formed anarray 25 consisting of a plurality of similar rib waveguides each curved and providing optical paths in parallel with each curved waveguide lying side by side in the array. A single waveguide from the array is shown in more detail at 26 in FIG. 3. This has a central curved region terminating in astraight input end 27 and astraight output end 28. It will be understood that such dispersive arrays may be used as multiplexers or demultiplexers and consequently the direction of light may be changed such that the input and output positions are interchangeable. Theinput end 30 of the array has thestraight portions 27 of each waveguide terminating along an arcuate surface of anoptical coupler 31. Thecoupler 31 comprises unetched silicon slab having the same depth as the ribs of the rib waveguides. The etched trenches along opposite sides of each rib terminate at two facing arcuate edges of thecoupler 31. Theends 30 of the array of waveguides terminate at one of the arcuate surfaces of the coupler marked 33 and theinput waveguide 21 terminates on the opposite arcuate face of the coupler marked 32. Theinput waveguide 21 is arranged to be directed at the centre of theends 30 of the waveguide array. Theends 30 of the waveguide array are themselves on thearcuate surface 33 which forms part of a circle of radius R. The facingarcuate surface 32 forms part of a circle of half the radius R but having its perimeter coincident with thearcuate surface 33 adjacent theends 30 of the waveguide array. Thestraight ends 27 of thewaveguide array 25 are inclined inwardly towards each other so as to focus at the end of theinput waveguide 21 on thearcuate edge 32 of thecoupler 31. - A similar
optical coupler 40 is provided between theother end 41 of thearray 25 and theoutput rib waveguides 22. Theends 41 of thearray 25 are spaced around a first arcuate edge of thecoupler 40, the arcuate edge forming part of acircle 42 having a radius R. Theoutput waveguides 22 have theirinner ends 43 terminating adjacent the furtherarcuate edge 44 forming part of afurther circle 45 having a radius of one half R. Thecircle 45 has its periphery coincident with the arcuate edge ofcircle 42 adjacent theends 41 of thewaveguide array 25. - The
straight ends 28 of thearray 25 are again inwardly inclined towards each other so as to focus onto the perimeter ofcircle 45 adjacent theends 43 of theoutput waveguides 22. Similarly theoutput waveguides 22 which are curved across thechip 20 havestraight end portions 43 inclined towards each other so as to be focussed onto the perimeter ofcircle 42 immediately adjacent theends 41 of the waveguides in thearray 25. - It will be seen that the circular arrangement of the rib ends on the
optical couplers circles - In operation it is desirable that the wavefront leaving the output end of the dispersive array is focussed onto the or each output waveguide. Despite the physical separation between adjacent curved waveguides in the
array 25, there will be some coupling of the wavefront towards the output end of the array due to the close physical proximity of adjacent waveguides. In the case of silicon rib waveguides the coupling of the wavefront between adjacent waveguides is much less than occurs with silica or with InP devices. The use of the Rowlands circle arrangement is such that the ends of theoutput waveguides 43 are located on thearc 44 which is much closer to theoutput ends 41 of the array than would be the case when using both arcs on a common circle. In cases where theoutput waveguides 43 join an optical coupler on an arc of thesame circle 42 as the arc on which thearray 25 terminates, much greater chip space is required. It will therefore be appreciated that in this example a Rowland circle arrangement theoutput waveguide 22 can be brought onto thearcuate surface 44 of a circle of only half the diameter thereby making the arrangement much more compact, although the coupling in the end regions of the dispersive array is weak. - The arrangement of the
optical coupler 40 is shown in greater detail in FIG. 4 and illustrates the focussing of thewaveguides 25 onto position 50 which is midway across the array ofoutput waveguides 22. Similarly theoutput waveguides 22 are inclined inwardly so as to focus onto point 51 which is located midway across the array ofwaveguides 25. This figure shows thecoupler region 40 as being part of the unetched silicon slab with each wave guide being formed as an unetched rib remaining between two trenches etched in the slab. The etched trenches terminate at thearcs couplers - The invention is not limited to the details of the foregoing example. For example, more than one
input waveguide 21 may be provided.
Claims (13)
1. A dispersive optical waveguide device comprising an array of curved silicon rib waveguides providing optical paths in parallel between a first optical coupler at one end of the array and a second optical coupler at an opposite end of the array, the ends of the array waveguides adjacent said second coupler being distributed around a first arcuate edge of said second coupler forming part of a first circle, and a plurality of connecting waveguides terminating at a second arcuate edge of said second coupler facing said first arcuate edge of the second coupler, said second arcuate edge forming part of a second circle having a radius of curvature which is half the radius of curvature of the said first circle and having its perimeter coincident with the perimeter of the first circle adjacent the said ends of the array waveguides.
2. A waveguide device according to claim 1 in which the said ends of the array waveguides are inclined to each other so as to focus at said second arcuate edge of the second coupler.
3. A waveguide device according to claim 1 or claim 2 in which said connecting waveguides are inclined towards-each other at said second arcuate edge so as to focus at said first arcuate edge of said second coupler.
4. A waveguide device according to any one of the preceding claims in which said first optical coupler has two facing arcuate edges, one adjacent an end of the waveguide array forming part of a third circle and the other forming part of a fourth circle, the fourth circle having a radius of curvature one half that of the third circle and having its perimeter coincident with the perimeter of the third circle adjacent said array of waveguides.
5. A waveguide device according to claim 4 in which an input waveguide is connected to the first optical coupler at the arcuate edge on said fourth circle facing said waveguide array.
6. A waveguide device according to claim 5 in which said input waveguide is a silicon rib waveguide.
7. A waveguide device according to any one of claims 4 to 6 in which said first and third circles have the same radius of curvature.
8. A waveguide device according to any one of claims 4 to 7 in which said second and fourth circles have the same radius of curvature.
9. A waveguide device according to any one of the preceding claims in which each of said first and second optical couplers comprise a slab region of silicon.
10. A waveguide device according to any one of the preceding claims in which said connecting waveguides each comprise a silicon rib waveguide.
11. A waveguide device according to any one of the preceding claims arranged to operate as a multiplexer or demultiplexer.
12. A waveguide device as claimed in any one of the preceding claims comprising a single integrated silicon chip device.
13. A waveguide device substantially as hereinbefore described with reference to and shown in the accompanying drawings.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0023700A GB2367635A (en) | 2000-09-27 | 2000-09-27 | Dispersive optical waveguide array |
GB0023700.8 | 2000-09-27 |
Publications (1)
Publication Number | Publication Date |
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US20020094167A1 true US20020094167A1 (en) | 2002-07-18 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US09/963,495 Abandoned US20020094167A1 (en) | 2000-09-27 | 2001-09-27 | Dispersive optical waveguide array |
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US (1) | US20020094167A1 (en) |
GB (1) | GB2367635A (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1688767A4 (en) * | 2003-11-28 | 2007-11-28 | Omron Tateisi Electronics Co | Multi-channel array waveguide diffraction grating type multiplexer/demultiplexer and method of connecting array waveguide with output waveguides |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
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KR100424688B1 (en) * | 1997-02-14 | 2004-07-23 | 니혼덴신뎅와가부시키가이샤 | A waveguide circuit, a method of manufacturing the same, and a waveguide circuit module |
GB2334594A (en) * | 1998-02-20 | 1999-08-25 | Fujitsu Telecommunications Eur | Arrayed waveguide grating device |
-
2000
- 2000-09-27 GB GB0023700A patent/GB2367635A/en not_active Withdrawn
-
2001
- 2001-09-27 US US09/963,495 patent/US20020094167A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
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GB0023700D0 (en) | 2000-11-08 |
GB2367635A (en) | 2002-04-10 |
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Owner name: BOOKHAM TECHNOLOGY PLC, UNITED KINGDOM Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ROBERTS, STEPHEN;PANDRAUD, GREGORY;REEL/FRAME:012629/0495;SIGNING DATES FROM 20020103 TO 20020108 |
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